THE PITUITARY BODY 



mammals water diuresis is markedly and specifically in- 

 hibited by the vasopressor principle; simultaneously certain 

 salts, particularly NaCl, are excreted at an increased rate. 

 Diuresis inhibition usually is attributed to an increased re- 

 absorption of water by the tubular epithelium of the kid- 

 neys (loop of Henle?). In addition, however. Eraser (1937) 

 has found that the oxytocic principle appears to cause an 

 increased secretion of urine in both "hydrated" and "nonhy- 

 drated" rats without clearly affecting the chloride in the urine. 

 Eraser could not demonstrate any diuretic effect of oxytocic 

 principle in the non-anesthetized dog with a fistula of the 

 bladder. (Whether or not water was administered is not 

 stated.) 



The observations of Unna and Walterskirchen (1935-36) 

 were made in non-anesthetized dogs with a permanent fistula 

 of the bladder. Of particular interest is their report on 

 Leerdiurese. The animals'" were fasted 16-20 hours but were 

 allowed water until 2 hours before the experiment. The in- 

 jection of as little as 0.01 unit of posterior-lobe extract sub- 

 cutaneously or o.oooi unit intravenously could cause a defi- 

 nite increase in the excretion of CI. If a diuresis appeared, it 

 was thought to be caused by the CI excreted. Both the CI 

 excretion and the diuresis were higher if the diet was high 

 in CI; likewise they were low in animals on a low CI diet. 

 Also Melville (1936) was of the opinion that a "salt-mobiliz- 

 ing" action is responsible for any diuretic action of vaso- 

 pressor hormone. In anesthetized or non-anesthetized dogs, 

 the diuretic effect of extract could be increased by the ad- 

 ministration by mouth or by intravenous infusion under 

 anesthesia of solutions of NaCl, KCl, or KNO3 but not 

 Na.SO,." 



Eurther investigations of the mechanism of the diuresis- 



'" Dogs weighing 6-12 kg. 



" See also Frey (1937) for a discussion of factors influencing the diuretic action 

 of posterior-lobe extract. PVey believed that increased glomerular filtration accounts 

 for the change. It is not possible to state that this view is correct. 



[266I 



